Merge parser and expressions into repository

actions-expressions/src/errors.ts

@@ -0,0 +1,52 @@
+import { Pos, Token, tokenString } from "./lexer";
+
+export const MAX_PARSER_DEPTH = 50;
+export const MAX_EXPRESSION_LENGTH = 21000;
+
+export enum ErrorType {
+  ErrorUnexpectedSymbol,
+  ErrorUnrecognizedNamedValue,
+  ErrorUnexpectedEndOfExpression,
+
+  ErrorExceededMaxDepth,
+  ErrorExceededMaxLength,
+  ErrorTooFewParameters,
+  ErrorTooManyParameters,
+  ErrorUnrecognizedContext,
+  ErrorUnrecognizedFunction,
+}
+
+export class ExpressionError extends Error {
+  constructor(private typ: ErrorType, private tok: Token) {
+    super(`${errorDescription(typ)}: '${tokenString(tok)}'`);
+
+    this.pos = this.tok.pos;
+  }
+
+  public pos: Pos;
+}
+
+function errorDescription(typ: ErrorType): string {
+  switch (typ) {
+    case ErrorType.ErrorUnexpectedEndOfExpression:
+      return "Unexpected end of expression";
+    case ErrorType.ErrorUnexpectedSymbol:
+      return "Unexpected symbol";
+    case ErrorType.ErrorUnrecognizedNamedValue:
+      return "Unrecognized named-value";
+    case ErrorType.ErrorExceededMaxDepth:
+      return `Exceeded max expression depth ${MAX_PARSER_DEPTH}`;
+    case ErrorType.ErrorExceededMaxLength:
+      return `Exceeded max expression length ${MAX_EXPRESSION_LENGTH}`;
+    case ErrorType.ErrorTooFewParameters:
+      return "Too few parameters supplied";
+    case ErrorType.ErrorTooManyParameters:
+      return "Too many parameters supplied";
+      case ErrorType.ErrorUnrecognizedContext:
+        return "Unrecognized named-value";
+    case ErrorType.ErrorUnrecognizedFunction:
+      return "Unrecognized function";
+    default: // Should never reach here.
+      return "Unknown error";
+  }
+}